Device and method for positioning a body part

ABSTRACT

A device and a method are disclosed for positioning a body part ( 16 ) on an analytical device ( 14 ) for body fluids includes a flexible compression element ( 24 ) for pressing against the body part ( 16 ) while increasing the pressure and a rigid support part ( 26 ) to hold the compression element ( 24 ) on a housing ( 12 ) of the analytical device ( 14 ). The compression element ( 24 ) has an engaging member ( 34 ) for the body part ( 16 ) which can be pressed into the housing ( 12 ) such that a withdrawal region ( 56 ) of the body part ( 16 ) is exposed in the interior ( 18 ) of the housing ( 12 ) in order to remove liquid.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of Intenational Application No.PCT/EP2005/005301 filed May 14, 2005, which claims benefit to GermanPatent Application 10 2004 024 970.9 filed May 14, 2004, both of whichare hereby incorporated by reference.

FIELD OF THE INVENTION

The invention concerns a device and a method for positioning a bodypart, in particular a finger pad on an analytical device for body fluidsand an appropriate analytical device according to the preamble of theindependent patent claims.

BACKGROUND

A system for withdrawing body fluid is known from DE 100 26 172 A1 inwhich a deformable double cone is used as a compression unit to increasethe inner pressure in a region of the pressed body part. In this processthe downward pressure is partially converted into a movement in asecondary direction with a component at right angles to the primarydirection until the upper and lower cone region rest against oneanother. In this state the constriction which ties off the body part islocated above the plate-like support member whereas the puncture orblood removal site still lies within the collapsed double cone. Thisrequires a point access for blood withdrawal with the risk that excessblood can contaminate the device. Moreover, the body part canaccidentally slip if the coefficient of friction between the compressionunit and the skin falls below a lower limit for example due to skinsweat or fat deposits. In this case a malfunction can also occur if thecompression unit completely folds through into the inside of the device.

SUMMARY

Starting from this the object of the invention is to avoid thedisadvantages occurring in the prior art and to improve a positioningdevice and an appropriate method such that a body part can be positionedin a reliable and defined manner free of interfering contours for anespecially planar liquid removal using simple means.

The combination of features stated in the independent patent claims isproposed to achieve this object. Advantageous embodiments and furtherdevelopments of the invention result from the dependent claims.

The invention is based on the idea of ensuring the body part is pressedas far as possible into the interior of the device. Accordingly theinvention proposes that the compression element has an engaging memberfor the body part which can be pressed into the housing such that awithdrawal region of the body part is exposed in the interior of thehousing opposite to a flat test field in order to remove liquid. In thismanner the free space in the interior of the device can be used to applyliquid to a flat substrate without requiring a liquid transport forexample by means of a capillary structure. The withdrawal below theedges of the housing allows a hygienic measurement process with smallamounts of liquid (blood or tissue fluid) while the low lying engagingmember ensures a stationary positioning. Moreover, a high positioningtolerance results from the flat uptake on the test field.

The engaging member can advantageously be pressed in up to the plane ofa boundary of the support part on the housing such that the protrudingor pinched off region of the body part is freely accessible.

For a further improvement of the positioning accuracy stop means areprovided to limit the pressing depth of the compression element.

A special aspect of the invention is that the compression element thathas a circular cross-section has a free outer edge that is widened by anoutwardly projecting stop bead. Thus a stop situation is achieved whenit is pressed inwards which reliably prevents a further inversion of thecompression element.

An advantageous embodiment provides that the compression element has twosubregions which converge in a conical manner towards the pressure axiswherein the distal subregion has a stop bead on its outside which abutsagainst the proximal subregion when it is pressed against the body part.In order to ensure that it is reliably stopped it is advantageous whenthe stop bead tapers preferably in a wedge-like manner away from thefree outer edge of the compression element.

Alternatively or in addition thereto it is also possible that thesupport part has an opening to press in the compression element and thaton the housing side an abutment extending into the area of the openingis attached to the support part in order to limit the depth ofimpression of the compression element. For a secure support it isadvantageous when the abutment is formed by a stop ring which tapersinto the opening of the support part.

In order to engage as deeply as possible it is advantageous when thecompression element is permanently connected to a rim of the opening inthe support part wherein the connecting area extends over the entireheight of the opening rim so that it is pushed in as deeply as possiblein the housing region during compression.

In order to optimize the force introduction it is advantageous when thearea connecting the support part and compression element is inclinedaway from a boundary surface of the support part on the housing wherethe angle between the incline and the boundary surface should be in therange of 50° to 70°, preferably 60°.

For the compression process it is also advantageous when the compressionelement in the initial state has an inner surface which tapers in akink-free manner towards a lateral edge of the support part on thehousing.

In order to improve the fit to a curved contour of the body part and tosecure the adhesion it is advantageous when the engaging member isformed by the inner edge of a concavely curved ring surface of thecompression element.

For the manufacture it is advantageous when the compression element ismoulded as a moulded part preferably as an injection moulded part ontothe prefabricated support part. In this connection the compressionelement can be attached to the support part by an adhesive bond and inparticular are formed by a primer.

The compression element is advantageously composed of silicon, rubber orpolyurethane. Silicon is preferably used for hygienic reasons.

In a constructionally advantageous embodiment the support part isconstructed as a dimensionally stable ring washer and especially onemade of metal.

A one-step manufacture can be achieved by designing the compressionelement consisting of a thermoplastic elastomer and the support partconsisting of plastic as a two component injection moulded part.

In order to allow an exchange for example to fit it to the size of thebody part or for cleaning, the support part can be inserted into ahousing receiving member in a detachable manner.

For a compact design of a portable device it is advantageous when thetotal width of the support part perpendicular to the pressing directionis less than 25 mm, preferably less than 20 mm.

Another aspect of the invention concerns an analytical device for bodyfluids and in particular for determining blood sugar comprising ahousing and a device for positioning a body part, in particular a fingerpad, comprising a preferably circular flexible compression element forpressing against the body part while increasing the pressure and a rigidsupport part to hold the compression element on the housing. It isproposed according to the invention that the compression element has anengaging member for the body part which can be pressed into the housingsuch that a withdrawal region of the body part is exposed in theinterior of the housing opposite to a flat test field in order to removeliquid. This allows the previously described advantages to be realizedin a compact portable device.

For storage purposes a test tape is preferably arranged in the interiorof the housing which has a plurality of test fields on a windablesupport tape. In addition a lancing device for insertion into thewithdrawal region of the body part and an analytical device fordetecting an analyte on a test field to which body fluid has beenapplied are arranged in the interior of the housing for an integratedsystem.

The test fields arranged consecutively on the test tape that ispreferably located in a cassette can advantageously be movedsuccessively into an active position with regard to the withdrawalregion of the body part, the lancing device and/or the analytical deviceby means of a tape transport device.

A further simplification is achieved by the fact that the lancing devicehas a distal pressing face to press a test field against the withdrawalregion of the body part.

In order to make the uptake of liquid more tolerant of positionespecially in the case of small amounts, it is particularly advantageouswhen the receiving area of the test field to which body fluid can beapplied is more than 2×5 mm², preferably about 5×20 mm².

With regard to the process the object mentioned above is achieved inthat the body part protrudes into the housing when it is pressed wherebya withdrawal region of the body part is kept free in the interior of thehousing opposite to a flat test field for liquid withdrawal.

In order to further improve the user friendliness it is advantageouswhen body fluid on the exposed withdrawal region of the body part isapplied to test fields stored on a test tape in the interior of thehousing.

In order to integrate the individual analytical steps, a lancing deviceis inserted into the withdrawal region in the interior of the housingwhereby body fluid dammed up under the increased inner pressure emergesfrom the generated puncture wound. In this connection it is advantageouswhen the lancing device and the test tape are removed from thewithdrawal region of the body part during a phase of liquid efflux.

The test tape that is preferably wound up in a cassette isadvantageously advanced such that an unused test field is moved to anactive position relative to the withdrawal region of the body part.

Another simplification of the process is achieved by applying body fluidthat has escaped from the withdrawal region of the body part to a testfield by a lateral excursion of the test tape.

The impression depth of the compression element is preferably limited bystop means.

It is also particularly advantageous when the compression element isheld on the housing as a replaceable part in a removable manner by meansof a rigid part of the support.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is further elucidated in the following on the basis of theembodiment examples shown schematically in the drawing.

FIG. 1 shows a portable analytical device for determining blood sugarcomprising a device for positioning a finger in a perspective view.

FIGS. 2 and 3 show the positioning device that can be removed from theinstrument in a perspective view and in an axial section.

FIG. 4 shows the positioning device onto which a finger has been pressedfor loading a test element in an axial section.

FIG. 5 shows another embodiment in a view corresponding to FIG. 3; and

FIG. 6 a to e show the process of blood withdrawal/analysis each in anaxial section.

DETAILED DESCRIPTION

The positioning device 10 shown in the drawing can be inserted into thehousing 12 of a portable blood sugar measuring instrument 14 as aneasily exchangeable inserted part in order to position a finger pad 16of a test person in the interior of the instrument 18 for bloodwithdrawal and analysis.

For this purpose the portable device 14 shown in FIG. 1 has a receivingmember 20 for the exchangeable positioning device 10. The device as anintegrated system comprises a lancing device 11 inside the instrument topuncture the finger pad and an analytical device 13 for determining thesugar content of the blood withdrawn at the puncture site (FIG. 6). Theresult that is determined can be shown to the user by a display unit 22.

As best shown in FIGS. 2 and 3, the positioning device 10 has a flexiblecompression element 24 to press against the finger pad 16 and adimensionally stable support part 26 to hold the compression element 24.The compression element 24 with a circular cross-section has twosubregions 30, 32 which converge conically towards the pressure axis 28.The sharp bend between these subregions 30, 32 forms an open engagingmember 34 to engage the finger pad 16 wherein the inner width in thearea of the opening 36 is reduced during the pressing movement and thussqueezes the free finger tip while increasing the pressure in order topromote the accumulation of blood.

For a better match to the finger contour the upper or distal subregion30 has a concavely curved inner ring surface 38. When the finger 16 ispressed on, this results firstly in a circular edge contact in the areaof the engaging member 34 with a high face pressure for an antislippositioning.

In order to reliably stop the pressing movement, a stop bead 40 ismoulded onto the free outer edge of the distal subregion 30 which tapersin a wedge-shaped manner towards the proximal subregion 32. In the stopposition the stop bead 40 is braced against the outer side 42 of thesubregion 32 and thus prevents further collapse of the compressionelement 24 in the pressing direction.

The support part 26 as a ring washer borders an opening 44 for thecompression element 24. The support part 26 is permanently connectedover its entire height and wall thickness to the rim of the opening 46of the compression element 24 by means of an adhesive bond. For afavourable force introduction the connecting surface 48 is arranged as aslope at an acute angle of about 60° to the boundary surface 50 of thesupport part on the housing. In order to achieve a larger impressiondepth the inner surface 52 of the proximal subregion 32 extends with asmooth contour and without sharp bends towards the boundary edge of therim of the opening 46 on the housing.

The compression unit 24 is made of silicon as a flexible moulded partwhereas the support part 26 consists of metal and preferably aluminium.The compression element can be moulded onto the support part placed inan injection moulding tool in an injection moulding process where aprimer on the contact area 48 increases the strength of the adhesivebond. Alternatively manufacture in a two-component injection mouldingprocess is also conceivable in which the compression unit 24 is mouldedfrom a thermoplastic elastomer and the support part 26 is moulded fromplastic in one process step to form a composite part.

FIG. 4 shows the end or stop position of the compression unit 24 whenthe finger 16 is pressed on. The wedge-shaped stop bead 40 fills theouter interspace between the subregions 30, 32 without gaps such thatcomplete collapse is prevented due to the incompressibility of theelastomer material even with a low coefficient of friction of the skin.

The bending site 54 is shifted downwards corresponding to the pressingdirection due to the deep connection of the proximal subregion 32 to therim of the opening 46. The engaging member 34 thus extends into theinterior 18 of the housing 12 and in any case under the boundary surface50 of the support part 26 on the housing. Accordingly a withdrawalregion 56 of the finger pad 16 is exposed in the interior of the housing18. After the puncture it is thus possible to remove an emerging drop ofblood 58 freely by a flat test field 60 without requiring a pointaccess. This type of automatic blood collection is particularly suitablein combination with a tape cassette system that can be used to transporta plurality of test fields 60 stored on a support tape 62 successivelyinto the engaging region of the body part 16.

In the embodiment shown in FIG. 5 the same parts have the same referencenumerals as described above. In addition an abutment 64 is providedwhich is attached to the face 50 of the support part 26 which bordersthe housing. The abutment 64 extends into the area of the opening 44 inorder to limit the impression depth of the compression element 24. Theabutment 64 in the area of the opening is bevelled downwards towards afree rim edge to form a stop face 66 for a form locking support that isbevelled in the opposite direction relative to the inner face 52 of thecompression element 24. Thus an additional positioning accuracy of thefinger tip 56 is achieved for blood withdrawal in the interior of thedevice.

FIG. 6 a to e show the process of blood withdrawal and analysis inindividual steps. In the device 14 the positioning device 10 is used asan exchangeable part whereas a test tape 70 and the lancing device 11are located under it in the interior of the device 18. The test tape 70has a plurality of test fields 60 which are arranged spaced apart in thetape direction on the carrier tape 62. The carrier tape 62 is providedwith lancing openings 72 between the test fields 60 for the lancingelement 74 that is pretensioned in the lancing device 11. The test tape70 is advantageously wound onto spools (supply spool and waste spool) ina cassette that is not shown.

When the finger tip 16 is pressed against the compression element 24,the blood capillaries in the squeezed region of the finger 76 are tiedoff while the withdrawal region 56 is kept clear in the interior of thedevice 18 for blood withdrawal (FIG. 6 b). For this purpose a puncturewound from which blood 78 can escape is generated by pushing the lancingelement 74 forwards through the opening 72. In order not to impede thedischarge of blood, the lancing device 11 and the test tape 70 are at adistance from the withdrawal region 56 during this phase that lasts afew seconds. The test tape 70 is positioned by winding on such that anunused test field 60 is moved opposite to the withdrawal region 56.

According to FIG. 6 d the discharged drop of blood 78 is transferreddirectly onto the receiving area of the test field 60 by laterallydeflecting the test tape 70 by a distal pressing face 80 of the lancingdevice 11 or by other means. Due to the dimensions of the area of thetest element 60, the positioning relative to the puncture wound is veryvariable whereas the direct access for blood uptake or “dabbing” avoidsa dead volume due to transport capillaries or such like.

As shown in FIG. 6 e the test field 60 with the applied blood 82 istransported by advancing the tape into the detection area of the opticalanalytical device 13. A test chemistry is disposed on the test field 60which reacts with an analyte in this case glucose in the blood 82 forexample with a colour change. This can be detected reflectometricallythrough the transparent carrier tape and be processed for display and/orstorage of the measured glucose value. The used test field 60 ishygienically disposed off on the waste spool of the cassette while afresh test field is provided again for the next measurement without theuser having to reach into the device.

1. Device for positioning a body part, in particular a finger pad, on ananalytical device for body fluids comprising a preferably circularflexible compression element for pressing against the body part whileincreasing the pressure and a rigid support part to hold the compressionelement on a housing of the preferably portable analytical device,characterized in that the compression element has an engaging member forthe body part which can be pressed into the housing such that awithdrawal region of the body part is exposed in the interior of thehousing opposite to a flat test field in order to remove liquid. 2.Device according to claim 1, characterized in that the engaging membercan be pressed in at least up to the plane of a boundary of the supportpart on the housing.
 3. Device according to claim 1, characterized inthat stop means are provided to limit the pressing depth of thecompression element.
 4. Device according to claim 1, characterized inthat the compression element with a circular cross-section has a freeouter edge that is widened by an outwardly projecting stop bead. 5.Device according to claim 1, characterized in that the compressionelement has two subregions which converge in a conical manner towardsthe pressure axis wherein the distal subregion has a stop bead on itsoutside which abuts against the proximal subregion when it is pressedagainst the body part.
 6. Device according to claim 4, characterized inthat the stop bead tapers preferably in a wedge-like manner away fromthe free outer edge of the compression element.
 7. Device according toclaim 1, characterized in that the support part has an opening to pressin the compression element and that an abutment extending into the areaof the opening region is attached to the housing side of the supportpart in order to limit the depth of impression of the compressionelement.
 8. Device according to claim 7, characterized in that theabutment is formed by a stop ring which tapers into the opening of thesupport part.
 9. Device according to claim 1, characterized in that thecompression element is permanently connected to a rim of the opening inthe support part wherein the connecting area extends over the entireheight of the rim of the opening.
 10. Device according to claim 1,characterized in that the area connecting the support part andcompression element is inclined away from a boundary surface of thesupport part on the housing where the angle between the incline and theboundary surface should be in the range of 50° to 70°, preferably 60°.11. Device according to claim 1, characterized in that the compressionelement in the initial position has an inner surface which tapers in akink-free manner towards a lateral edge of the support part on thehousing.
 12. Device according to claim 1, characterized in that theengaging member is formed by the inner edge of a concavely curved ringsurface of the compression element.
 13. Device according to claim 1,characterized in that the compression element is moulded as a mouldedpart, preferably as an injection moulded part onto the prefabricatedsupport part.
 14. Device according to claim 1, characterized in that thecompression element consisting of a thermoplastic elastomer and thesupport part consisting of plastic are formed as a two componentinjection moulded part.
 15. Device according to claim 1, characterizedin that the compression element can be attached to the support part byan adhesive bond and in particular by an adhesive bond formed by aprimer.
 16. Device according to claim 1, characterized in that thecompression element is composed of silicon, rubber or polyurethane. 17.Device according to claim 1, characterized in that the support part isconstructed as a dimensionally stable ring washer and especially onemade of metal.
 18. Device according to claim 1, characterized in thatthe support part can be inserted into a housing receiving member in adetachable manner.
 19. Device according to claim 1, characterized inthat the total width of the support part perpendicular to the pressingdirection is less than 25 mm, preferably less than 20 mm.
 20. Ananalytical instrument for body fluids in particular for blood sugardetermination characterized by a positioning device for a body partaccording to claim
 1. 21. Analytical instrument for body fluids and inparticular for determining blood sugar comprising a housing and a devicefor positioning a body part, in particular a finger pad, comprising apreferably circular flexible compression element for pressing againstthe body part while increasing the pressure and a rigid support part tohold the compression element on the housing, characterized in that thecompression element has an engaging member for the body part which ispressed into the housing during liquid withdrawal such that a withdrawalregion of the body part is exposed in the interior of the housingopposite to a flat test field.
 22. Analytical instrument according toclaim 21, characterized in that-a test tape is preferably arranged inthe interior of the housing which has a plurality of test fields on awindable support tape.
 23. Analytical instrument according to claim 21,characterized in that a lancing device for insertion into the withdrawalregion of the body part is arranged in the interior of the housing. 24.Analytical instrument according to claim 21, characterized in that ananalytical device for detecting an analyte on a test field to which bodyfluid has been applied is arranged in the interior of the housing. 25.Analytical instrument according to claim 21, characterized in that thetest fields arranged consecutively on the test tape that is preferablylocated in a cassette can be moved successively into an active positionwith regard to the withdrawal region of the body part, and/or thelancing device and/or the analytical device by means of a tape transportdevice.
 26. Analytical instrument according to claim 21, characterizedin that the lancing device has a distal pressing face to press a testfield against the withdrawal region of the body part.
 27. Analyticalinstrument according to claim 21, characterized in that the receivingarea of the test field to which body fluid can be applied is more than2×5 mm² and preferably 5×20 mm².
 28. Method for analysing body fluids inparticular for determining blood sugar in which a body part, inparticular a finger pad, is positioned on an analyser wherein the bodypart is pressed against a preferably circular flexible compressionelement in order to increase the internal pressure wherein thecompression element has an engaging member for the body part which canbe pressed into the housing and the body part penetrates into thehousing when it is pressed down such that a withdrawal region of thebody part is kept clear in the interior of the housing opposite to aflat test field in order to remove liquid.
 29. Method according to claim28, characterized in that body fluid on the exposed withdrawal region ofthe body part is applied to test fields stored on a test tape in theinterior of the housing.
 30. Method according to claim 28, characterizedin that a lancing device is inserted into the withdrawal region in theinterior of the housing whereby body fluid dammed up under the increasedinner pressure emerges from the generated puncture wound.
 31. Methodaccording to claim 28, characterized in that the lancing device and thetest tape are removed from the withdrawal region of the body part duringa phase of liquid efflux.
 32. Method according to claim 28,characterized in that a test tape preferably wound up in a cassette isadvantageously wound on such that an unused test field is moved to anactive position relative to the withdrawal region of the body part. 33.Method according to claim 28, characterized in that a body fluid thathas escaped from the withdrawal region of the body part is applied to atest field by a lateral excursion of the test tape.
 34. Method accordingto claim 28, characterized in that the impression depth of thecompression element is limited by stop means.
 35. Method according toclaim 28, characterized in that the compression element is held on thehousing as a replaceable part in a removable manner by means of a rigidpart of the support.